2. Passive or Active Transport:Passive or Active Transport:
Passive Transport - does not require cellPassive Transport - does not require cell
energyenergy
Examples: Diffusion, Facilitated diffusion andExamples: Diffusion, Facilitated diffusion and
Osmosis Osmosis
Active Transport Requires cell energy (ATP)Active Transport Requires cell energy (ATP)
Examples: Carrier mediated active transport,Examples: Carrier mediated active transport,
Endocytosis and ExocytosisEndocytosis and Exocytosis
3. Methods of Transport:Methods of Transport:
1. Diffusion:1. Diffusion: the random movement of particlesthe random movement of particles
of a solute from an area of higher concentrationof a solute from an area of higher concentration
to an area of lower concentration.to an area of lower concentration.
Particles always moveParticles always move withwith (down) a(down) a concentrationconcentration
gradientgradient (the difference in concentrations across a(the difference in concentrations across a
membrane).membrane).
Passive transport.Passive transport.
4. EquilibriumEquilibrium
Diffusion stops atDiffusion stops at equilibriumequilibrium (when the concentrations across(when the concentrations across
a membrane are equal).a membrane are equal).
The movement of molecules continues at equilibrium but the #The movement of molecules continues at equilibrium but the #
of molecules moving across the membrane remains the same.of molecules moving across the membrane remains the same.
The rate of transport is dependent on:The rate of transport is dependent on:
1) if the material is solid, liquid or gas.1) if the material is solid, liquid or gas.
2) the size of the molecules.2) the size of the molecules.
3) temperature3) temperature
Examples of molecules that can diffuse through the bilayer:Examples of molecules that can diffuse through the bilayer:
carbon dioxide, oxygen, water but very, very slowly.carbon dioxide, oxygen, water but very, very slowly.
6. OsmosisOsmosis
Osmosis:Osmosis: the diffusion of water through athe diffusion of water through a
selectively permeable membrane.selectively permeable membrane.
Passive transportPassive transport
Water molecules move from a higher concentrationWater molecules move from a higher concentration
OF WATER to a lower concentration OF WATER.OF WATER to a lower concentration OF WATER.
Water will move to where there is a greater amountWater will move to where there is a greater amount
of solute because there is less water thereof solute because there is less water there
7. Isotonic SolutionIsotonic Solution
Isotonic solutions:Isotonic solutions: thethe
concentration of solute inside andconcentration of solute inside and
outside of the cell is the same.outside of the cell is the same.
Isotonic:Isotonic:
Water in = Water outWater in = Water out
No net movement of water.No net movement of water.
Molecules in equilibrium.Molecules in equilibrium.
Normal state for animal cells.Normal state for animal cells.
Cell in homeostasis.Cell in homeostasis.
8. Hypotonic SolutionHypotonic Solution
Hypotonic solutions:Hypotonic solutions: the concentration of solute isthe concentration of solute is
lower outside the cell than inside the cell.lower outside the cell than inside the cell.
Have more water outside the cell so water moves into the cellHave more water outside the cell so water moves into the cell
Causes an increase in pressure inside the cell: calledCauses an increase in pressure inside the cell: called turgorturgor
pressure (plants) or osmotic pressure (animals).pressure (plants) or osmotic pressure (animals).
Increase in pressure in animal cells causes them to swell orIncrease in pressure in animal cells causes them to swell or
even burst; gives plant cells shape and support.even burst; gives plant cells shape and support.
9. Example HypotonicExample Hypotonic
Hypotonic:Hypotonic:
Water enters cell.Water enters cell.
Cell swells and burstsCell swells and bursts
(cytolysis).(cytolysis).
Give plant cells shapeGive plant cells shape
and support.and support.
10. Hypertonic SolutionHypertonic Solution
Hypertonic solutions: the concentration ofHypertonic solutions: the concentration of
solute is higher outside the cell than inside thesolute is higher outside the cell than inside the
cell.cell.
Have more water inside the cell so water moves outHave more water inside the cell so water moves out
of the cellof the cell
Causes a drop in turgor or osmotic pressure: calledCauses a drop in turgor or osmotic pressure: called
plasmolysis.plasmolysis.
Plasmolysis causes animal cells to shrivel up andPlasmolysis causes animal cells to shrivel up and
plants to wilt.plants to wilt.
11. Hypertonic ExampleHypertonic Example
Hypertonic:Hypertonic:
Water exits cell.Water exits cell.
Cell shrinksCell shrinks
(plasmolysis) due to (plasmolysis) due to
water loss.water loss.
12. The effects of osmotic pressureThe effects of osmotic pressure
14. The effects of osmotic pressure in aThe effects of osmotic pressure in a
plant cellplant cell
15. Facilitated DiffusionFacilitated Diffusion
Particles always moveParticles always move withwith
(down) a(down) a concentrationconcentration
gradientgradient..
Uses transport/channelUses transport/channel
proteins.proteins.
Passive transport.Passive transport.
Usually for specific moleculesUsually for specific molecules
such as glucose.such as glucose.
Facilitated diffusion stops atFacilitated diffusion stops at
equilibriumequilibrium..
16. Active transportActive transport
Active Transport:Active Transport: requires energy in the formrequires energy in the form
of ATP.of ATP.
Capable of moving solute particles against the conc.Capable of moving solute particles against the conc.
gradient (from low conc. to high conc.)gradient (from low conc. to high conc.)
Uses transport/carrier proteins (protein pumps)Uses transport/carrier proteins (protein pumps)
embedded in the plasma membrane.embedded in the plasma membrane.
Carrier proteins are specific for the molecules thatCarrier proteins are specific for the molecules that
they allow through. The carrier protein changesthey allow through. The carrier protein changes
shape which requires energy (ATP).shape which requires energy (ATP).
17. Active Transport against theActive Transport against the
concentration gradientconcentration gradient
18. Active TransportActive Transport
Endocytosis:Endocytosis: a process of taking material intoa process of taking material into
the cell by means of infoldings, or pockets, ofthe cell by means of infoldings, or pockets, of
the cell membrane (usually putting them into athe cell membrane (usually putting them into a
vacuole).vacuole).
Phagocytosis -“Cell eating”Phagocytosis -“Cell eating”
Nonspecific moleculesNonspecific molecules
Intake of solidsIntake of solids
Pinocytosis –”Cell Drinking”Pinocytosis –”Cell Drinking”
Nonspecific moleculesNonspecific molecules
Intake of small droplets of liquidIntake of small droplets of liquid
19. Active TransportActive Transport
Exocytosis (reverse endocytosis):Exocytosis (reverse endocytosis): a process ina process in
which the membrane of the vacuole surroundingwhich the membrane of the vacuole surrounding
the material fuses with the cell membrane,the material fuses with the cell membrane,
forcing the contents out of the cell.forcing the contents out of the cell.
